The present invention relates to thermally insulated containers, and, more particulary, to insulated containers which are not rigid but rather have soft, flexible sides.
Soft-sided insulated containers have a number of advantages over rigid thermally insulated containers. Soft-sided insulated containers can be compressed such as when not in use, or deformed to fit into a particular size of opening. If a soft-sided insulated container is dropped or collides against other objects, less damage will generally occur, both to the contents of the container and to the object(s) collided against. Soft-sided insulated containers are generally lightweight. Despite use which may involve rigorous wear and tear, soft-sided insulated containers can be made durable and attractive for an extended period of time. With these various advantages, soft-sided insulated containers are often preferable over containers with rigid walls.
While soft-sided insulated containers have many advantages, the very nature of the soft sides contributes to a number of problems as compared to rigid containers that need to be addressed. Most obviously, because the containers are formed of flexible materials rather than rigid materials, a whole new set of materials needs to be used for the container. Because the dimensions of the container are subject to the flexibility of the material, dimensions can change during use of the container, and many rigid structures (such as hinges, latches, locks etc.) are not possible.
For example, covers of soft-sided insulated containers cannot be formed for a tight (i.e., slight interference) fit into the body of the container. Instead, the tolerance associated with locational placement of the cover of a soft-side container is one or more orders of magnitude larger than with rigid containers. The uncertainty of locating the cover with respect to the container can lead to thermal problems including the escape of heat or cold from the container through gaps between the cover and the body of the container.
To secure the cover with respect to the body of the container, many soft-sided containers use a zipper connection between the cover and the body. As currently designed, zippers do not possess the thermal resistance needed for many applications. The zippered seam can create a location of significant thermal loss from the container.
The design of a soft-sided container needs to be efficient and inexpensive, from the standpoint of both the cost of materials and the amounts of materials used. The soft-sided container should also be easily manufactured and minimize the labor necessary to create the container.